The \(\mathcal {H}_\infty \) -norm constraints on the (also FIR) transfer matrix \(\mathbf {\Delta }\)  can then be enforced via semidefinite programming (see Theorem 5.8 in [1]}), potentially introducing a nontrivial computational burden. However, we note that one can replace the \(\mathcal {H}_\infty \) -norm constraint in optimization problems (REF ) and (REF ) with any induced norm constraint. A particularly appealing option is the \(\ell _1 \rightarrow \ell _1\)  induced norm (which defines the \(\mathcal {L}_1\) -norm of the transpose system), as this norm decomposes columnwise. As shown in [2]}, [3]}, the resulting robustness constraints are linear and embarrassingly parallelizable. We defer this extension to future work.
